The prior art is generally cognizant of racks or cases adapted to hold and exhibit spools of thread. For example, Cutler, U.S. Pat. No. 242,607, shows an exhibiting case for spools having drawers the bottom of which include side by side troughs or channels arranged in various ways to accept and hold spools. Williams, U.S. Pat. No. 1,182,827, shows a device for holding spools of thread in such a way that thread may be drawn from the spools without removing them from the cup-shaped shelves of the device. The prior art is also cognizant of devices in which identical packages or articles are stacked vertically and so held that the bottom-most article may be pushed backwardly off a shelf and fall down into a chute from which it may be removed, whereupon the entire stack of articles shifts downwardly to expose the next article to being so pushed off the shelf. An example of such device is shown in Compton, U.S. Pat. No. 2,474,142.
Certain problems not solved by the prior art are encountered in the storage of many spools holding material of diverse size, color, and texture, such as a working inventory of sewing threads, when the spools are to be arranged so that a user may readily select a desired spool and easily extract it from the holder. A vertical shelving unit might be selected wherein several shelves are arranged one above the other with the spools held end-to-end in a row that extends from one side of the holder to the other. By this arrangement, the thread of all the spools may be examined at a glance. An analogous arrangement is seen in Cutler. However, for a person to extract a spool from the holder, he must somehow grasp the spool. Thus, space for one's fingers must be left either at the ends of the spools or above them. If space is left at the ends, fewer spools may be stored on each shelf than would otherwise be the case. If headroom is left above each row of spools so that the user's finger may be inserted between the spool and the shelf next above, allowing him to pull the spool forward and off of the shelf, considerable space is wasted vertically. Therefore, when such an arrangement is employed, fewer spools may be stored in a given space than would be possible if they could be placed snugly end-to-end with little or no headroom above the spools and the next higher shelf.